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authorSuzuki K Poulose <suzuki.poulose@arm.com>2017-04-03 15:12:43 +0100
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2017-04-27 09:09:33 +0200
commit2a60bb635236ead6437b37a5b4085da1e33962b1 (patch)
parente2587fba99118f2f4506b37b4766d7a4cca1465e (diff)
kvm: arm/arm64: Fix locking for kvm_free_stage2_pgd
commit 8b3405e345b5a098101b0c31b264c812bba045d9 upstream. In kvm_free_stage2_pgd() we don't hold the kvm->mmu_lock while calling unmap_stage2_range() on the entire memory range for the guest. This could cause problems with other callers (e.g, munmap on a memslot) trying to unmap a range. And since we have to unmap the entire Guest memory range holding a spinlock, make sure we yield the lock if necessary, after we unmap each PUD range. Fixes: commit d5d8184d35c9 ("KVM: ARM: Memory virtualization setup") Cc: Paolo Bonzini <pbonzin@redhat.com> Cc: Marc Zyngier <marc.zyngier@arm.com> Cc: Christoffer Dall <christoffer.dall@linaro.org> Cc: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com> [ Avoid vCPU starvation and lockup detector warnings ] Signed-off-by: Marc Zyngier <marc.zyngier@arm.com> Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com> Signed-off-by: Christoffer Dall <cdall@linaro.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
1 files changed, 12 insertions, 0 deletions
diff --git a/arch/arm/kvm/mmu.c b/arch/arm/kvm/mmu.c
index f91ee2f27b41..01cf10556081 100644
--- a/arch/arm/kvm/mmu.c
+++ b/arch/arm/kvm/mmu.c
@@ -300,6 +300,14 @@ static void unmap_range(struct kvm *kvm, pgd_t *pgdp,
next = kvm_pgd_addr_end(addr, end);
if (!pgd_none(*pgd))
unmap_puds(kvm, pgd, addr, next);
+ /*
+ * If we are dealing with a large range in
+ * stage2 table, release the kvm->mmu_lock
+ * to prevent starvation and lockup detector
+ * warnings.
+ */
+ if (kvm && (next != end))
+ cond_resched_lock(&kvm->mmu_lock);
} while (pgd++, addr = next, addr != end);
@@ -738,6 +746,7 @@ int kvm_alloc_stage2_pgd(struct kvm *kvm)
static void unmap_stage2_range(struct kvm *kvm, phys_addr_t start, u64 size)
+ assert_spin_locked(&kvm->mmu_lock);
unmap_range(kvm, kvm->arch.pgd, start, size);
@@ -824,7 +833,10 @@ void kvm_free_stage2_pgd(struct kvm *kvm)
if (kvm->arch.pgd == NULL)
+ spin_lock(&kvm->mmu_lock);
unmap_stage2_range(kvm, 0, KVM_PHYS_SIZE);
+ spin_unlock(&kvm->mmu_lock);